In 1609, Galileo constructed the first powerful telescope and started observing the heavens, which led to many monumental discoveries. He published his initial findings on the moon and the stars in 1610 in a brief treatise titled "Sidereus Nuncius" ("Starry Messenger"). An original printing of this publication is held by the Rare Book and Special Collections Division of the Library of Congress. NASA scientist Michelle Thaller discusses "Galileo: 400 Years of the Telescope." This illustrated lecture, the first in a series of programs in 2010, is presented through a partnership between the Library's Science, Technology and Business Division and NASA Goddard Space Flight Center.Speaker Biography: Michelle Thaller obtained a doctorate in observational astrophysics through Georgia State University, specializing in the life and death of massive stars. She has spent time in Australia and South America working on the world's foremost telescopes, and has also been an observer with the Hubble Space Telescope, the ROSAT X-Ray Satellite and the International Ultraviolet Explorer Satellite. She spent more than 10 years at the California Institute of Technology and NASA Jet Propulsion Laboratory in Pasadena as the manager of the Spitzer Space Telescope's outreach program.For more information, visit http://www.loc.gov/today/cyberlc/feature_wdesc.php?rec=4851.